Concrete arch



Patented 1an. lo, |899.

E. THACHER.

CONCRETE ARCH.

(Application med oct. 1e, 189e.)

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WITNESSES.

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NITED STATES PATENT CFFICE.

EDWIN TIIACHER, OF DETROIT, MICHIGAN.

CONCRETE ARCH.

srEcIFIoATIoN forming part of Letters Patent No. 617,615, dated January1o, v11399.

Application led October 16, 1896. Serial No. 609,053. (No model.)

To all whom, it 71u03/ concern,.-

Beit known that I, EDWINv THACHER, a citizen of the United States,residing at Detroit, county of Vayne, State of Michigan, have invented acertain new and useful Improvement .in Concrete Arches; and I declarethe following to be a full, clear, and exact de scription of theinvention, such as will enable others skilled in the art to which itpertains to make and use the same, reference being had to theaccompanying drawings, which form a part of this speciflcation.

My invention relates to concrete arches for bridges or vault-covering orfor spanning openi'n gs in building construction; and it has for itsobject au improved arch structure in which iron or steel bars areembedded in concrete near the outer and inner surfaces of the arch insuch a manner as to assist the concrete in resisting the thrusts andbending moments to which the arch is subjected.

By my invention I provide, first, for an effective connection betweenthe bars and the concrete, employing lugs, dowels, bolts, or rivets,which pass through the bars and project into the concrete, in which theyare embedded, and thereby reinforce the adhesion between the metal andthe concrete and prevent any end movement of the bar through theconcrete, so that the'complete crushing or shearing of the concrete musttake place before a separation can be effected; second, I employ bars ofsuch a form that they can be readily and cheaply spliced if a greaterlength of bar is required than that which can be conveniently rolled orshipped; third, I provide bars that can be manufactured at a small costand as a standard or stock article and can be readily bent when used tothe curve of the arch into which they are to enter. Consequently theycan be stored or shipped in straight form. generally I arrange the barsin pairs, which are usually disposed so that one of the pair restsvertically above the other member of the pair, although I do notconsider this manner of disposing the bars as essential in all cases. The bars act as the anges of beams to resist bending moments, whereas theshearing stresses, which are small, are taken by the concrete alone. Intheir normal condition the bars and the concrete act together,

In ordinary structures and' and the Work done by each depends on itsmoment of inertia and modulus of elasticity; butif the concrete isdefective and has a tendency to crack the bars will greatly aid inresisting such tendency, and if a crack should take place the relationof the parts will be` changed and the bars will do thejwork of theconcrete and prevent the falling of the structure.

In the drawings, Figure 1 represents in vertical longitudinal sectionone-half of a bridgearch. Fig. 2 is a cross-section at the lines C D ofFig. 1. Fig. 3 is a plan showing onefourth of an arch. Fig. 4 is anenlarged cross-section of a portion of the arch. Figs. 5 and 6 showsmall portions of two styles of bars.

Similar -numbers refer to similar parts throughout the figures.

The abutment l, rthe arch 2, and the spandrel-iilling 3 constitute thecomplete structure, in which et indicates the metal bars (iron or steel)embedded in the concrete near the lower face and the upper face thereof.These bars extend well in to the abutment or pier 1 and are providedwith projections extending in either direction from the surface of thebars. The projections maybe produced either in the form of lugs madeintegral with the bars, as shown in Fig. 6, or in the form of dowels orrivets placed in and secured to the bar after it has been rolled. Theyshould project far enough to give to the bara good hold on the concrete.For small structures, in which but few bars are required, I shouldprefer the form shown in Fig. 5, in which a dowel or rivet pin withupset heads are placed through holes in the bar. In larger structures,where many bars are required, I should prefer a specially-constructedbar like that shown in Fig. 6.

The use of the double bars enables me to not only bend them at the timethey are required for use to any desired arc of a circle, but enables meto bend them so that the different members of each pair are differentlyarched, and, furthermore, it'enables me to completely embed thelowermost member of the pair before the uppermost member is placed,thereby securing an intimate contact between the bar and the concretewithout requiring the great particularity of filling and IOO rainniingunder that is necessary where a bent I-beam with extending Iianges ise1nployed and necessarily put in place before any of the concrete isfilled in around it.

That I claim is- 1. The combination with abutments, and a concrete archspanning the intervening space, of a series o'f metal bars, in pairs,one bar of each pair above the other, near the intrados and extrados ofthe arch, and extending Well into the abutlnents, each bar of a pairbeing independent of the other, substantiall y as described.

A2. The combination with abutments, and a solid concrete arch spanningthe intervening space, of a series of metal bars in pairs one bar ofeach pair vertically above the other, near lthe intrados and extrados ofthe arch, and extending Well into the abutinents,

each bar of a pair being independent of the zo other, and each bar beingilat and provided with projections, substantially as described.

3.Y The combination with abutnients, and a concrete arch spanning thespace between the abutments, of a series of metal bars in pairs, one barof each pair above the other bar, near the extrados and intrados of thearch, each bar of the pair being independent of the other and one bar ofeach pair extending Well into the abutment, substantially as described.

In testimony whereof Isign this specification in the presence of twoWitnesses.

EDNVIN TEACHER.

Witnesses:

D. W. BRADFORD, VIRGINIA M. GLOUGH.

